The present invention comprises a new and distinct cultivar of Hydrangea plant known by the varietal name ‘Horsonn’. The new variety was discovered in 2001 in a breeding program in Dresden, Germany. The purpose of the breeding program was to develop Hydrangeas having light pink flowers. The new variety is the result of a cross between ‘Königstein’ (female parent, unpatented) and breeding selection no. 30-89/3 (male parent, unpatented). The inflorescence colour and foliage of the new variety are similar to its female parent, but ‘Horsonn’ exhibits a different vigour and inflorescence diameter. ‘Horsonn’ is a mophead like ‘Königstein’, but their stem quality and root system differ. ‘Horsonn’ has a similar inflorescence diameter to its male parent, but differs in inflorescence colour and growth habit. The new variety was first asexually reproduced in 2001 via propagation by cuttings in Germany. The new variety has been trial and field tested in Germany and has been found to retain its distinctive characteristics and remain true to type through successive propagations.
The following traits distinguish ‘Horsonn’ as a new and distinct cultivar from other Hydrangea varieties known to the breeder:                1. Inflorescence size;        2. Stem quality;        3. Vigour;        4. Strong root system; and        5. Branching habit.        